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Tafoni, produced by physicochemical weathering of sandstones, are abundant in the Cerro Colorado (Córdoba province, Argentina). Many of the rock shelters are decorated with rock art of high heritage significance. This art belongs to semisedentary communities from the Late Prehispanic Period (ca. 1550–350 AP). They include morphologies inherited from more humid ancient climates combined with current weathering processes. Evolutionary relief study established that tafoni formation is a product of inherited past wetter climates. Mineralogical and petrographic analyses were performed on samples collected from the sandstones and from various morphologies, weathering residues, and wall and ceiling concretions at four rock shelters, Cueva del Indio, Ricci, Quitilipi, and La Trampa. Gypsum and other salts that are not part of the unaltered rock but the result of weathering reveal the magnitude of hydroclastic and haloclastic processes. These activities form active granular disintegration, flaking, and spalling, and impinge on some painted panels. Mapping the distribution of weathering features and processes at each rock shelter enables the planning of interventions to mitigate and alleviate the effects caused by infiltration of water through rock discontinuities, fractures, and overhangs. It also allows decreasing the accumulation of dust and minimizing muddy water flowing over the paintings. These actions are aimed at retarding the progression of rock art degradation and the visible loss of some paintings. [ABSTRACT FROM AUTHOR]

A comprehensive morphostratigraphic and chronological study of the complete set of Holocene tephras from Tafí and Santa María valleys (northwestern Argentina), including analyses of compositional characteristics, is presented. Five ash tephras are recognized: V0 (El Rincón), V1a (Carreras 1a ash), V1b (Carreras 1b ash), V2a (Carreras 2 ash), and V2b (El Paso 3 ash). Two of them (V1b and V2b) are described for the first time in the study area. The new 14C and accelerator mass spectrometry ages presented, along with the previously published information, allows for the establishment of a chronological framework. The V0 tephra was deposited in the Early Holocene (about 10,000 yr BP), V1a and V1b were deposited in the Middle Holocene (about 4200 and 3500 yr BP, respectively), and V2a and V2b were deposited in the Late Holocene (after about 800 yr BP). The mineralogical, textural, and geochemical characterizations of the five tephras suggest that their tephra provenance was mainly from the back-arc region. However, the determination of the exact source of each tephra requires more accurate high-resolution tephrochronological studies. At least five major eruptions affected the Tafí and Santa María valleys in the last 10,000 yr. [ABSTRACT FROM AUTHOR]

Soil compaction is a problem recently identified as one of the main constraints on the maize surface of the municipality of Villaflores in the region of The Frailesca, Chiapas, due to this, it needs to be studied with greater precision. The objective of this study was to characterize the problem of compaction on the mechanized surface cultivated with corn in the New Mexico commn. We studied 177 plots, in which the apparent density, organic matter and texture were determined at the depths of 0-20 and 20-40 cm. The owners of the properties were interviewed to obtain information about their cultivation practices and corn productivity levels. The results show that 83.3% of the studied area presented superficial compaction and 94.6% compaction in the subsoil (plow floor). The producers pointed out that in years with critical periods of drought the yields are reduced by 58%, which is correlated with the decrease of the porosity as a result of the compaction. The main causes of the compaction were the intensive tillage with machinery 100% of the sites, the very low content of 100% organic matter and the type of soil (luvisols and acrisols). The attention of the compaction problem requires a comprehensive corrective and preventive strategy that should take as a central element the elevation of the contents of organic matter, to reverse the current unsustainable management of the land. [ABSTRACT FROM AUTHOR]

On 13 June 2015, the London Volcanic Ash Advisory Centre (VAAC) warned the Buenos Aires VAAC about a possible volcanic eruption from the Nevados Ojos del Salado volcano (6879 m), located in the Andes mountain range on the border between Chile and Argentina. A volcanic ash cloud was detected by the SEVIRI instrument on board the Meteosat Second Generation (MSG) satellites from 14:00 UTC on 13 June. In this paper, we provide the first comprehensive description of this event through observations and numerical simulations. Our results support the hypothesis that the phenomenon was caused by wind remobilization of ancient pyroclastic deposits (ca. 4.5 ka Cerro Blanco eruption) from the Bolsón de Fiambalá (Fiambalá Basin) in northwestern Argentina. We have investigated the spatiotemporal distribution of aerosols and the emission process over complex terrain to gain insight into the key role played by the orography and the condition that triggered the long-range transport episode. Numerical simulations of windblown dust were performed using the ARW(Advanced Research WRF) core of the WRF (Weather Research and Forecasting) model (WRF-ARW) and FALL3D modeling system with meteorological fields downscaled to a spatial resolution of 2 km in order to resolve the complex orography of the area. Results indicate that favorable conditions to generate dust uplifting occurred in northern Fiambalá Basin, where orographic effects caused strong surface winds. According to short-range numerical simulations, dust particles were confined to near-ground layers around the emission areas. In contrast, dust aerosols were injected up to 5-6 km high in central and southern regions of the Fiambalá Basin, where intense ascending airflows are driven by horizontal convergence. Long-range transport numerical simulations were also performed to model the dust cloud spreading over northern Argentina. Results of simulated vertical particle column mass were compared with the MSG-SEVIRI retrieval product. We tested two numerical schemes: with the default configuration of the FALL3D model, we found difficulties to simulate transport through orographic barriers, whereas an alternative configuration, using a numerical scheme to more accurately compute the horizontal advection in abrupt terrains, substantially improved the model performance. [ABSTRACT FROM AUTHOR]

On the 13 June 2015, the London Volcanic Ash Advisory Centre (VAAC) warned the Buenos Aires VAAC about a possible volcanic eruption from the Nevados Ojos del Salado volcano (6879 m), located in the Andes mountain range on the border between Chile and Argentina. A volcanic ash cloud was detected by the SEVIRI instrument on board the Meteosat Second Generation (MSG) satellites from 14:00 UTC on 13 June. Further studies concluded that the phenomenon was caused by remobilization of ancient pyroclastic deposits (circa 4.5 Ka Cerro Blanco eruption) from the Bolsón de Fiambalá (Fiambalá Basin) in northwestern Argentina. In this paper, we provide the first comprehensive description of the dust episode through observations and numerical simulations. We have investigated the spatio-temporal distribution of aerosols and the emission process over complex terrain to gain insight into the key role played by the orography and the condition that triggered the long-range transport episode. Numerical simulations of windblown dust were performed using the WRF-ARW/FALL3D modeling system with meteorological fields downscaled to a spatial resolution of 2 km in order to resolve the complex orography of the area. Results indicated that favourable conditions to generate dust uplifting occurred in northern Fiambalá Basin, where orographic effects caused strong surface winds. According to short-range numerical simulations, dust particles were confined to near-ground layers around the emission areas. On the other hand, dust aerosols were injected up to 5-6 km high in central and southern regions of the Fiambalá Basin, where intense ascending airflows are driven by horizontal convergence. Long-range transport numerical simulations were also performed to model dust cloud spreading over northern Argentina. Results of simulated vertical particle column mass were compared with the MSG-SEVIRI retrieval product. We tested two numerical schemes: with the default configuration of the FALL3D model, we found difficulties to simulate transport through orographic barriers, whereas an alternative configuration, using a numerical scheme to more accurately compute the horizontal advection in abrupt terrains, substantially improved the model performance. [ABSTRACT FROM AUTHOR]

Establishing the factors that control the pathways of magma ascent is an important issue in the study of monogenic mafic volcanism since it provides information about the relationship between the source of the ascending magma and the regional and local tectonic frameworks. We have quantitatively analyzed the spatial distribution of the volcanic centers in the monogenic volcanic fields (MVFs) of the Southern Puna using Nearest-Neighbor Analysis to assess the degree of randomness between individual centers. We also performed alignment analysis which highlights the structural weaknesses that magmas use to ascend. We integrate these novel data with published structural, petrologic, and geophysical data to propose a source-to-surface model which explains the spatial distribution of monogenic mafic centers of the Southern Puna. We find that MVFs display two distinct spatial patterns related to different magmatic production rates. Specifically, in those areas where the magmatic production is long-lasting and relatively high, the magma exerts strain rates suffciently high to reactivate pre-exisiting discontinuities with random orientations with respect to the current local stress conditions. As a result the volcanic centers are arranged with a clustered spatial distribution. We define these as MVFs controlled by magmatism or high flux fields (MVFs-M). On the other hand, low magmatic production rates tend to produce areas where mafic centers display a Poisson distribution, because strain rates are only sufficient to reactivate pre-existing discontinuities that are nearly parallel to the maximum compressive stress. This latter group is defined as MVFs controlled by tectonism or low flux fields (MVFs-T). Available petrological and geophysical data indicate that both groups are fed by a complex lower crustal MASH zone where magma production is associated with lithospheric foundering and subduction-related mantle melting. Spatial distribution of the MVFs in the Southern Puna are also affected by the development of upper crustal magma storage zones. • Bivariate Gauss-kernels Density allow to define the number of MVF in the Southern Puna. • Nearest-Neighbor and Two-Azimuth quantitative methods reveal the spatial distribution of the MVFs. • Two main types of MVFs were identified: dominated by magmatism and dominated by tectonism. • Both groups are feed by a complex source related to lithospheric foundering and subduction. • Spatial distribution is later affected by lithospheric processes. [ABSTRACT FROM AUTHOR]

This paper presents a detailed geological map at the 1:20,000 scale of the Tocomar basin in the Central Puna (north-western Argentina), which extends over an area of about 80 km2 and displays the spatial distribution of the Quaternary deposits and the structures that cover the Ordovician basement and the Tertiary sedimentary and volcanic units. The new dataset includes litho-facies descriptions, stratigraphic and structural data and new 234U/230Th ages for travertine rocks. The new reconstructed stratigraphic framework, along with the structural analysis, has revealed the complex evolution of a small extensional basin including a period of prolonged volcanic activity with different eruptive centres and styles. The geological map improves the knowledge of the geology of the Tocomar basin and the local interplay between orogen-parallel thrusts and orogen-oblique fault systems. This contribution represents a fundamental support for in depth research and also for encouraging geothermal exploration and exploitation in the Puna Plateau region. [ABSTRACT FROM AUTHOR]